A conventional cotton harvester includes a mobile frame having two or more harvesting units supported at a forward end thereof. A lift assembly supports the harvesting units on the frame of the harvester. To promote movement of the harvester from one location to another, the lift assembly supports the harvesting units for vertical movement between a lower operational position and a raised transport position. To facilitate servicing thereof and different row spacings therebetween, the harvesting units are laterally adjustable across the forward end of the harvester frame. When the harvesting units are laterally adjusted in skip row patterns, the lateral spacing between adjacent harvesting units may range from 40 to 64 inches.
Each harvesting unit on the harvester includes a harvesting mechanism. A typical harvesting mechanism includes a pair of picker rotor assemblies mounted to the side of a plant passage allowing cotton plants to pass through the harvesting unit as the harvester is driven across the field. At its upper end, each harvesting unit further includes a drive mechanism including a gearbox for imparting rotary movement to the harvesting mechanism.
The drive mechanism of each harvesting unit is driven from a drive assembly mounted on the frame of the harvester. To facilitate cotton removal while minimizing damage to the cotton plants, the drive assembly drives the harvesting units in timed relation to the ground speed of the harvester. A typical drive assembly uses a hydrostatic drive mechanism driven by the engine of the harvester for concurrently driving the harvester and the harvesting units More specifically, the hydrostatic drive mechanism is connected to and drives a transmission of the harvester and a pair of laterally spaced drive shafts extend from the drive assembly to individually drive the harvesting units.
It is known to provide a drive assembly wherein laterally spaced gearboxes are provided as an integral part and at opposite ends of a drive assembly housing. Each gearbox is interconnected to a harvesting unit by a fore-and-aft extending drive shaft. The housing and gearboxes of the drive assembly are designed with lubricant passageways therebetween to provide adequate lubricant between the housing and gear mechanisms and bearings in the gearboxes. Although serving an identical function to the gearboxes on the harvesting units, the gearboxes of heretofore known drive assemblies were limited to use at opposite ends of the drive assembly housing and were not interchangeable in other areas of the harvester. Accordingly, there was a substantial duplication of mechanisms within the harvester.
While the compactness of the heretofore known drive assembly offered spatial benefits, certain drawbacks were also inherent with such a compact design. As will be appreciated, the compactness of the heretofore known drive assembly provided limited lateral spacing between the gearboxes. The spacing between the gearboxes on the drive assembly was substantially less than the lateral spacing between adjacent harvesting units arranged in a skip row pattern. Accordingly, the drive shafts extending forwardly from the gearboxes were angularly disposed to compensate for the lateral misalignment between the gearbox and the harvesting unit. Depending on the severity of the drive shafts angular position, in some instances there was substantial power loss resulting from the geometry of the drive shaft relative to the respective gearbox. Such misalignment between the gearboxes and the harvesting units mandated use of a constant velocity drive shaft for transferring rotary power from the drive assembly to the harvesting unit. As will be appreciated, use of a constant velocity drive shaft as compared to a cardan drive shaft substantially increases the manufacturing costs of the drive assembly and, thus, increases the overall cost of the machine.
Thus, there is a need and a desire for a cotton harvester drive system which is designed to facilitate transfer of rotary power therethrough and is quickly and readily adaptable to changes in row spacings of the harvesting units.